Method of destroying insects with pyrethrum



Sept. 12, 1933.

W. S. BURGESS ET AL METHOD OF DESTROYING INSECTS WITH PYRETHRUM FiledMarch 8, 1935 2 Sheets-Sheet 1 INVENTOR Wa/ler 0". 52/

HI! Ill 5% o/kzfgz ATTORNEY j Sept. 12, 1933. w. s. BURGESS Er u. l,926,579

METHOD OF DESTROYING INSECTS WITH PYRETHRUM Filed March 8, 1933 2Sheets-Sheet 2 INVENTOR Patented Sept. 12, 1933 METHOD OF DESTROYINGINSECTS WITH PYRETHRUM Walter S. Burgess and Earl K. Golley, BentonHarbor, Mich.

Application March 8, 1933. Serial No.

- Claims. (Cl. 167-24) This application is a continuation in part of ourpatent application Serial No. 563,312, filed September 17,1931, withcertain improvements in details.

The objects of the invention are:

First, to provide an improved method and process of destroying insectswith pyrethrum.

Second, to provide such an improved method and process that is effectivein destroying insects in a closed space, such as a room, in which theinsecticide diffuses and enters all of the cracks and crannies where theinsects are wont to hide.

Third, to provide a method and process in which the maximum effect ofthe material is secured, thereby effecting economy of material.

Fourth, t

-"trated in the accompanying drawings, inwhich:

Fig. 1 is a detail side elevation view of our complete apparatus readyto plug in on, an electric lamp socket.

Fig. 2 is a plan view of the cap part detached.

Fig. 3 is an enlarged detail vertical sectional view through ourcomplete apparatus.

Fig. 4. is a vertical sectional view through the spray head of thedifiusing and distilling apparatus, taken on line H of Fig. 5.

Fig. 5 is a detail line 55 of Fig. 4.

Fig. 6 is a detail view of the head as constructed without adjustablefeature.

T e parts will be identified by their numerals of eference which are thesame in all the views.

1 is the main reservoir, preferably a strong glass jar. 2 is the metalcap screw threaded and sealed thereon. 3 is an electric heater unitdisposed in the main reservoir. to heat the water 4 contained therein.-5 is the electric connection for the unit connected to the cap or cover2. 6 is the filler plug. 7 is the relief valve. 8 is the container for apyrethrum concentrate 9. 10 is the connection to the spray or atomizerhead 11 leading from the steam space of the reservoir to the said sprayhead 11. 12 is the supply pipe leading up from the interior of thecontainer 8 to supply liquid concentrate to the head 11.

The spray head 11 of brass is of considerable mass toaccumulate heat.Steam delivers into a chamber 13 therein from which delivers a steamtransverse sectional view on jet 14 out through the spray aperture 15from the mixing chamber 16. Tube 12 leads up into the chamber 17 in thespray head, which is connected by the spray nozzle 18 to the mixingchamber 16. r 1

Giving attention to certain details, the chamber 16 is formed by a cap161 which is screw threaded onto a nipple 111 which projects slightly ina nozzle at 112. The bore 14 is drilled with a number 68 drill and is.031 of an inch in diameter. The bore 15 is drilled with a number 65drill and is .035 of an inch in diameter, or .004 of an inch larger thanthe bore 14. The bore 18 is drilled with a number 70 drill and is .028of an inch in diameter. The space between the nozzle 112 and the bore 15in the cap 161 is, at the minimum,- .006 of an inch. The chamber 16 isan annular space around the same.

The relief valve 7 is set at about 8 lb. pressure and the temperature ofthe steam is consequently considerably above boiling point, .or 212Fahr. The head 11 presenting a; considerable mass of metal isconsequently quite strongly heated by the hot steam (and is a heatreservoir) ,to just what temperature it is impossible to estimate, butthe relations of the parts are given and the temperature resulting ishigh enough to do the work. While the temperature certainly very closelyapproaches the boiling point, it, in operation, in no v way damages thepyrethrins or pyrethrum solu- ,tion or concentrate. The solution orconcentrate 9 is a kerosene solution made from pyrethrum flowers andkerosene or mineral oil and is a usual manufactured product known bythat name and commercially sold as pyrethrum concentrate. This worksexceedingly well with this apparatus. The best authorities at thepresent time assert that the pyrethrins or active principle of pyrethrumis not soluble in water to any appreciable extent.

While the pyrethrum concentrate, which theoretically contains a verysmall percent of the pyrethrins or active principle, gives satisfactoryresults under our process, we are aware that a much weaker solution canbe made use of with corresponding results. In place of kerosene ormineral oil as a solvent we are very clear that any effective solventfor the pyrethrum will be effective in this position, it being desirablethat the solvent be volatile at a different temperature from the water.It is our belief that in the operation of this apparatus an attenuatedstream of the dissolved pyrethrins or pyrethrum principle is preheatedby the steam as it passes to the no spray head and is taken up by acomparatively that point, but the atmosphere of the room, particularlywhere it is distributed, appears shortly to contain a cloud which iscertainly impregnated with the pyrethrum material. As soon as the waterevaporates from this cloud, the pyrethrum material is released, andwould certainly, if solid, be in a more finely divided condition thanhad been accomplished by any' known means. From the action it appearsthat the pyrethrum material has been volatilized intoa vapor which hasthe diffusion properties of a gas (or it may be it has been convertedinto a gas) and diffuses like a gas. It is impossible, in view of theminute quantity, to have any effective chemical determination on thisquestion. It has been indicated by authorities that a temperatureapproaching the boiling point of water (212 F.) causes a chemical breakdown in the pyrethrins. We do not know that the pyrethrins are notbroken down into some other material by the action of our apparatus, butif so it is a material apparently that is as toxic to insect life as thepyrethrins and apparently even more so. That is, there is a specialdevelopment of pyrethrum active principle or a new product or compound.We have stated our theoriesv in this matter so that they may beunderstood.

In the operation of our process and apparatus for the destruction ofroaches the material at once penetrates into all recesses and cranniesthat have any air space connection to the body of .the room. This isdone where no pressure has been exerted by the spray from the apparatus.It is simply done by the diffusion. In the case of a metallic protectingshell or bell of an electric fixture, if there are roaches behind it,they at once come out, being driven out by the action of the materialwhich has permeated through the narrow space accessible. Roaches arounda door casing entirely concealed from view at once come out. Roachesbehind baseboards at a point where no possible visible vapor hasreached, at once come out into the open and die. We refer to this asevidence of the fact that what we have produced isa gas or a gaseousvapor having the diffusion properties of a gas. The minute quantitywhich does the work makes it impossible of any efiective determinationor chemical analysis that we have been able to accomplish or that wehave been able to find out how to accomplish.

We wish to distinguish our apparatus and process from steam ,atomizersand their action. The object of a steam atomizer is to make use of thepressure and volume of the steam to disintegrate a liquid. The liquid,unless it is quitehighly volatile, is simply broken up into par ticles,that is, atomized. and the steam may serve to some extent as a carrier.However, the steam usually has the same effect as a jet of air and isnot quite so efficient because it immediately condenses. v

We also wish to distinguish our apparatus and process from the usualconstruction of spray gun which are piston air pumps which deliver a jetlimitation because where a roomis infested with roaches and is treatedwith our apparatus, they come out from the crannies and in a case of badinfestation, the floor of a room will be completely covered with deadroaches so that very frequently it is not possible to walk across thefloor of such a room without crushing numerous roaches under your feet.I

To compare with the action of a spray gun, our apparatus and process arevery efl'ective where an oil solution containing one per cent of theactive principle of pyrethrum is made use of. Our experiencedemonstrates that with such a solution, a substantial effect is obtainedby evaporating and converting one ounce of water for an ounce of thesolution; that the efiectiveness increases to a maximum when we convertthree ounces of. water to steam in the treatment of one ounce of 1%solution of pyrethrum; that very good work is done'when six ounces ofwater is converted to steam for each ounce of 1% pyrethrum solution.This shows a wide range of efliciency for the apparatus and process.

With this treatment, one ounce of 1% solution of pyrethrum, a usualstrength of pyrethrum concentrate, will, when treated with three ouncesof water converted to steam, that is 5,100 volumes of steam to the ounceof concentrate, or 510,000 times the volumeof active principle,effectively treat a room of 10,000 cubic feet capacity, that is. a room10 x 10 x 100. It will be seenvthat in each cubic foot of room treated,if the distribution is perfect, there will be one millionth part of anounce of the active principle of pyrethrum.

The treatment for the destruction of moths needs to be exceedinglythorough and repeated at intervals of a 'few days forseveral times,because the treatment is not eifective in destroying the insects eggsand moths are, to quite an extent, protected by whatever they aredestroying. 1

We have indicated precisely the dimensions of our apparatus. Thisapparatus has been demonstrated as of the highest efficiency in a year'scommercial exploitation, so that'in discussing the action of our device,we are not discussing a theory but actual practice.

We desire to claim the'method and process specifically and we alsodesire to claim the same. broadly.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:

1. The method of destroying insects in a closed space such as a roomcomprising steam atomizing a solution of the active principle ofpyrethrum by directing a jet of steam into said space and introducingsaid solution into said jet ing a solution of the active principle ofpyrethrum by directing a jet of steam into said space and introducing asmall continuous stream of said solution into said jet whereby theproduct is projected into and diffuses in said space.

3. The method of destroying insects in a closed space such as a roomcomprising steam atomizing a solution in mineral oil of the activeprinciple of pyrethrum by directing a jet of steam into said space andintroducing said solution into said jet whereby the product is projectedinto and difl'uses in said space.

4. The method of destroying insects in a closed space such as a roomcomprising treating the active principle of pyrethrum by steamatomization of a solution of said active principle with.

steam of a mass from approximately one hundred to six hundred times thatof the active principle bydirecting a jet of said-steam into said spaceand introducing said solution into said

